Eight speed dual clutch transmission

ABSTRACT

A transmission is connectable to an input member and includes an output transfer gear, first and second shaft members, first, second and third countershaft members, a plurality of co-planar gear sets, and a plurality of torque transmitting devices. The torque transmitting devices include a plurality of gears, synchronizer assemblies and a dual clutch assembly. The transmission is operable to provide at least one reverse speed ratio and a plurality of forward speed ratios between the input member and the output member.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/515,168, filed Aug. 4, 2011. The entire contents of the aboveapplication are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to transmissions and more particularly toa compact, dual clutch multiple speed transmission having at least threecountershafts to establish eight or more gear speeds.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission having countershafts and co-planargear sets uses countershaft gears with a different, dedicated gear pairor set to achieve each forward speed ratio. Accordingly, the totalnumber of gears required in this typical design is two times the numberof forward speeds, plus three for reverse. This necessitates a largenumber of required gear pairs, especially in transmissions that have arelatively large number of forward speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needin the art for a transmission having improved packaging while providingdesirable gear ratios and torque ranges.

SUMMARY

The present invention provides a transmission is connectable to an inputmember and includes an output member, first and second shaft members,first, second and third countershaft members, a plurality of co-planargear sets, and a plurality of torque transmitting devices. The torquetransmitting devices include a plurality of synchronizer assemblies anda dual clutch assembly. The transmission is operable to provide at leastone reverse speed ratio and a plurality of forward speed ratios betweenthe input member and the output member.

In another aspect of the present invention, the transmission includes atransmission housing.

In another aspect of the present invention, the transmission includes adual clutch assembly having a first clutch, second clutch, and a clutchhousing connectable to an engine output member. The clutch housing isrotationally supported within the transmission housing.

In another aspect of the present invention, the transmission includes afirst, second, third, fourth and fifth gear set in four planes.

In another aspect of the present invention, the transmission includes afirst transmission input member rotatably supported in the transmissionhousing.

In another aspect of the present invention, the transmission includes asecond transmission input member rotatably supported in the transmissionhousing. The second transmission input member is concentric with thefirst transmission input member and at least partially surrounds thefirst transmission input member. The selective engagement of the secondclutch of the dual clutch assembly transfers torque form the clutchhousing to the second transmission input member.

In another aspect of the present invention, the transmission includesfirst, second and third countershafts each rotatably supported withinthe transmission housing and spaced apart from and parallel with thefirst and second transmission input members.

In another aspect of the present invention, the transmission includesfive synchronizer assemblies for selectively coupling at least one ofthe gears of the first, second, third, fourth and fifth gear sets withat least one of the first, second and third countershafts.

In another aspect of the present invention, the selective engagement ofthe first and second clutches of the dual clutch assembly interconnectsthe dual clutch housing with at least one of the first and the secondtransmission input members and the selective engagement of at least oneof the five synchronizer assemblies establishes at least one of eightforward speed ratios.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings wherein like referencenumbers refer to the same component, element or feature.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a schematic view of an embodiment of an eight speedtransmission having a dual clutch, two transmission input shafts, threecountershafts, a plurality of gear sets and a plurality ofsynchronizers, in accordance with the present invention.

DESCRIPTION

Referring to the FIGURE, a multiple speed transmission is generallyindicated by reference number 10. The transmission 10 is connectable toan input member 12 and has an output member or gear 14. In the presentembodiment, the input member 12 is a shaft and the output member 14 is agear, however those skilled in the art will appreciate that the inputmember 12 may be components other than shafts and the output member 14may be a component, such as a shaft, other than a gear.

The input member 12 is continuously connected with an engine 16 or othertorque producing machine to provide a driving torque to input member 12.The output member or gear 14 rotatably drives a differential assembly18. The differential assembly 18 transfers torque delivered by outputmember 14, ultimately, to a pair road wheels (not shown).

The transmission 10 includes a housing 19 that at least partiallyencloses a gearing arrangement 20. The gearing arrangement 20 includesvarious shafts or members, co-planar intermeshing gear sets, a dualclutch assembly, and selectively engageable synchronizers, as will bedescribed herein. For example, the gearing arrangement 20 includes afirst transmission input shaft or member 22, a second transmission inputshaft or member 24, a first countershaft 26, a second countershaft 28and a third countershaft 30. The second transmission input shaft ormember 24 is a hollow shaft that is concentric with and overlies thefirst transmission input shaft or member 22. The first countershaft 26,the second countershaft 28 and the third countershaft 30 are each spacedapart from and parallel with the first and second transmission inputshaft members 22, 24. The first and second transmission input shafts 22,24 define a first axis of rotation, the first countershaft 26 defines asecond axis of rotation, the second countershaft 28 defines a third axisof rotation and the third countershaft 30 defines a fourth axis ofrotation. The position and location of countershafts 26 and 28 relativeto first and second transmission input shafts 22, 24 areinterchangeable.

A dual clutch assembly 32 is connectable between the input member 12 andthe first and second transmission input shaft members 22, 24. The dualclutch assembly 32 includes a clutch housing 34 connectable for commonrotation with the input member 12. Further, the dual clutch assembly 32has first and second clutch elements or hubs 36 and 38. Clutch elements36 and 38 together with the clutch housing 34 are configured to form afriction clutch, as is known in the art as a dual clutch. Morespecifically, clutch elements 36, 38 and the clutch housing 34 havefriction plates mounted thereon or otherwise coupled thereto thatinteract to form a friction clutch. The clutch element 36 is connectedfor common rotation with the first transmission input shaft or member 22and the clutch element 38 is connected for common rotation with thesecond transmission input shaft or member 24. Thus, selective engagementof clutch element 36 with the clutch housing 34 connects the inputmember 12 for common rotation with the first transmission input shaftmember 22. Selective engagement of clutch element 38 with the clutchhousing 34 connects the input member 12 for common rotation with thesecond transmission input shaft member 24. It should be appreciated thatwhile the dual clutch assembly 32 is shown in the Figure as a wet clutchassembly, the dual clutch assembly 32 may be a dry clutch assemblywithout departing from the scope of the present invention.

The gearing arrangement 20 also includes a plurality of co-planar,meshing gear sets 40, 50, 60, 70 and 80. The present inventioncontemplates that the plurality of co-planar, meshing gear sets 40, 50,60, 70 and 80 may be arranged axially along transmission input shafts22, 24 in an order other than that which is shown in the FIGURE andstill be within the scope of the invention. Co-planar gear set 40includes a first pinion gear 42, a second pinion gear 44 and thirdpinion gear 46. First pinion gear 42 is rotatably fixed and connectedfor common rotation with the second transmission input shaft member 24and meshes with second pinion gear 44 and third pinion gear 46. Secondpinion gear 44 is selectively connectable for common rotation with thefirst countershaft member 26. It should be appreciated that first piniongear 42 may be a separate gear structure fixed to the secondtransmission input shaft member 24 or gear teeth/splines formed on anouter surface of the second transmission input shaft member 24 withoutdeparting from the scope of the present invention. Third pinion gear 46is selectively connectable for common rotation with the secondcountershaft member 28. Gear set 40 is disposed proximate a wall 48 ofthe transmission housing 19 that is on a front or side of thetransmission 10 proximate the dual clutch assembly 32.

Co-planar gear set 50 includes first pinion gear 52, second pinion gear54 and third pinion gear 56. First pinion gear 52 is rotatably fixed andconnected for common rotation with the second transmission input shaftmember 24 and meshes with second pinion gear 54 and third pinion gear56. Second pinion gear 54 is selectively connectable for common rotationwith the second countershaft member 28. Third pinion gear 56 isselectively connectable for common rotation with the first countershaftmember 26. Gear set 50 is positioned adjacent gear set 40.

Co-planar gear set 60 includes first pinion gear 62, second pinion gear64 and third pinion gear 66. First pinion gear 62 is rotatably fixed andconnected for common rotation with the first transmission input shaftmember 22 and meshes with second pinion gear 64 and third pinion gear66. Second pinion gear 64 is selectively connectable for common rotationwith the second countershaft member 28. Third pinion gear 66 isselectively connectable for common rotation with the first countershaftmember 26. Gear set 60 is disposed adjacent gear set 50.

Co-planar gear set 70 includes first pinion gear 72 and second piniongear 74. First pinion gear 72 is rotatably fixed and connected forcommon rotation with the first transmission input shaft member 22 andmeshes with second pinion gear 74. Second pinion gear 74 is selectivelyconnectable for common rotation with the first countershaft member 26.Gear set 70 is positioned adjacent gear set 60.

Aligned along the same plane as defined by gear set 70, transmission 10also includes a gear set 80. Gear set 80 includes a reverse gear 76 andpinion gear 78. Reverse gear 76 is selectively connectable for commonrotation with the second countershaft member 28 and meshes with piniongear 78 and second pinion gear 74 of gear set 70. Pinion gear 78 isselectively connectable for common rotation with the third countershaftmember 30.

Further, a first countershaft transfer gear 100 is rotatably fixed andconnected for common rotation with the first countershaft member 26. Asecond countershaft transfer gear 110 is rotatably fixed and connectedfor common rotation with the second countershaft member 28. A thirdcountershaft transfer gear 112 is rotatably fixed and connected forcommon rotation with the third countershaft member 30. Firstcountershaft transfer gear 100 is configured to mesh with output member14, the second countershaft transfer gear 110 is configured to mesh withoutput member 14 and third countershaft transfer gear 112 is configuredto mesh with output member 14. However, the first countershaft transfergear 100, the second countershaft transfer gear 110 and thirdcountershaft transfer gear 112 do not mesh with each other.

A park gear 114 is provided for placing transmission 10 in a park modethat prevents output member 14 from rotating. The park gear is shownrotationally fixed to third countershaft 30, however, park gear 114 maybe rotationally fixed to the first or second countershaft members 26, 28as well. Moreover, the axial location of the park gear along the first,second or third countershaft members 26, 28 or 30 may be changed inaccordance with available packaging space.

With continued reference to the FIGURE, the transmission 10 furtherincludes a plurality of selectively engageable synchronizer assemblies150, 152, 154, 156 and 158. Synchronizers 150, 152, 154 and 156 aredouble sided synchronizers and generally include a shift fork (notshown) that is bi-directionally translated by an actuator (not shown)into at least two engaged positions and a neutral or disengagedposition. In the present embodiment, synchronizer 150 is selectivelyactuatable to connect gear 44 for common rotation with the firstcountershaft member 26 and is selectively actuatable to connect gear 56for common rotation with the first countershaft member 26. Synchronizer152 is selectively actuatable to connect for common rotation gear 46with the second countershaft member 28 and is selectively actuatable toconnect for common rotation gear 54 with the second countershaft member28. Synchronizer 154 is selectively actuatable to connect for commonrotation gear 66 with the first countershaft member 26 and isselectively actuatable to connect for common rotation gear 74 with thefirst countershaft member 26. Synchronizer 156 is selectively actuatableto connect for common rotation gear 64 with the second countershaft 28and is selectively actuatable to connect for common rotation gear 76with the second countershaft member 28.

Synchronizer 158 is a single sided synchronizer and generally includes ashift fork (not shown) that is bi-directionally translated by anactuator (not shown) into at least one engaged position and a neutral ordisengaged position. Synchronizer 158 is selectively actuatable toconnect for common rotation gear 78 with the third countershaft member30.

The transmission 10 is capable of transmitting torque from the inputshaft 12 to the output gear member 14 in at least eight forward torqueratios and at least one reverse torque ratio. Each of the forward torqueratios and the reverse torque ratio is attained by selective engagementof the dual clutch assembly 32 and one or more of the synchronizerassemblies 150, 152, 154, 156 and 158. Those skilled in the art willreadily understand that a different speed ratio is associated with eachtorque ratio.

It should be appreciated that each individual gear set 40, 50, 60, 70and 80 provides one or more forward and/or reverse gear ratios uponselective engagement of the synchronizer assemblies 150, 152, 154, 156and 158. It should also be appreciated that a particular forward orreverse speed ratio may be achieved by different combinations ofsynchronizer and associated gear sets without departing from the scopeof the present invention.

For example, to establish the reverse torque ratio, clutch element 36 isengaged and synchronizer 156 is activated. Clutch element 36 couples theinput member 12 with the first transmission input shaft member 22.Synchronizer 156 connects gear 76 to the second countershaft member 28.More specifically, input torque from the input shaft 12 is transferredthrough the dual clutch assembly 32 to the first transmission inputshaft member 22, through pinion gear 72 to gear 74, through gear 74 togear 76, from gear 76 to the second countershaft member 28 throughsynchronizer 156, then to second countershaft transfer gear 110 and fromsecond countershaft transfer gear 110 to the output member 14.

To establish a first forward torque ratio (i.e. a 1st gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 with the first transmission input shaftmember 22. Synchronizer 154 couples gear 74 to the first countershaftmember 26. Input torque from the input member 12 is transferred throughthe dual clutch assembly 32 to the first transmission input shaft member22 to pinion 72. Pinion 72 transfers torque to gear 74 which transfersthe torque to the first countershaft member 26 through synchronizer 154and from the first countershaft member 26 to first countershaft transfergear 100 and then from first countershaft transfer gear 100 to theoutput member 14.

To establish a second forward torque ratio (i.e. a 2nd gear), clutchelement 38 is engaged and synchronizer 152 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates pinion 42. Synchronizer 152 couples gear 46 tothe second countershaft member 28. Accordingly, input torque from theinput member 12 is transferred through the dual clutch assembly 32 tothe second transmission input shaft member 24, through pinion 42 to gear46, from gear 46 to synchronizer 152, from synchronizer 152 to thesecond countershaft member 28 and from the second countershaft member 28to the second countershaft transfer gear 110 and the output member 14.

To establish a third forward torque ratio (i.e. a 3rd gear), clutchelement 36 is engaged and synchronizer 158 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates pinion 72. Synchronizer 158 couples gear 78 tothe third countershaft member 30. Thus, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thefirst transmission input shaft member 22, through pinion 72 to gear 74,through gear 74 to gear 76, through gear 76 to gear 78, from gear 78 tosynchronizer 158, from synchronizer 158 to the third countershaft member30, from the third countershaft member 30 to the third countershafttransfer gear 112 and then from third countershaft transfer gear 112 tothe output member 14.

To establish a fourth forward torque ratio (i.e. a 4th gear), clutchelement 38 is engaged and synchronizer 150 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates pinion 42. Synchronizer 150 couples gear 44 tothe first countershaft member 26. Thus, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thesecond transmission input shaft member 24 to pinion 42, then from pinion42 to gear 44, from gear 44 to synchronizer 150, from synchronizer 150to the first countershaft member 26, from the first countershaft member26 to first countershaft transfer gear 100 and then from firstcountershaft transfer gear 100 to the output member 14.

To establish a fifth forward torque ratio (i.e. a 5th gear), clutchelement 36 is engaged and synchronizer 156 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates pinion 62. Synchronizer 156 couples gear 64 tothe second countershaft member 28. Input torque from the input member 12is transferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to pinion 62, from pinion 62 to gear 64, from gear 64 to thesecond countershaft member 28 through synchronizer 156 to secondcountershaft transfer gear 110 and from second countershaft transfergear 110 to the output member 14.

To establish a sixth forward torque ratio (i.e. a 6th gear), clutchelement 38 is engaged and synchronizer 152 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates pinion 52. Synchronizer 152 couples gear 54 tothe second countershaft member 28. Thus, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thesecond transmission input shaft member 24 to pinion 52, then from pinion52 to gear 54, from gear 54 to synchronizer 152, from synchronizer 152to the second countershaft member 28, from the second countershaftmember 28 to second countershaft transfer gear 110 and then from secondcountershaft transfer gear 110 to the output member 14.

To establish a seventh forward torque ratio (i.e. a 7th gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates pinion 62. Synchronizer 154 couples gear 66 tothe first countershaft member 26. Input torque from the input member 12is transferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to pinion 62, from pinion 62 to gear 66, from gear 66 to thefirst countershaft member 26 through synchronizer 154 to firstcountershaft transfer gear 100 and from first countershaft transfer gear100 to the output member 14.

To establish an eighth forward torque ratio (i.e. an 8th gear), clutchelement 38 is engaged and synchronizer 150 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates pinion 52. Synchronizer 150 couples gear 56 tothe first countershaft member 26. Thus, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thesecond transmission input shaft member 24 to pinion 52, then from pinion52 to gear 56, from gear 56 to synchronizer 150, from synchronizer 150to the first countershaft member 26, from the first countershaft member26 to first countershaft transfer gear 100 and then from firstcountershaft transfer gear 100 to the output member 14.

Again, it should be appreciated that any one of the gear sets of gearsets 40, 50, 60, 70 and 80 may be changed in size and number gear teethor gear pitch to produce a certain forward and reverse torque ratiowithout departing from the scope of the present invention.

The present invention contemplates that a variety of torque ratios(i.e., the ratio of torque of the output member 14 to the input member12) and ratio steps are achievable through the selection of tooth countsof the gears of the transmission 10. The present invention has manyadvantages and benefits over the prior art. For example, the presentconfiguration provides eight speeds plus a reverse gear ratio with onlyfour co-planar gear sets. Thus, a transmission having a more simplifiedactuation and control system, reduced mass and cost and improvedpackaging is achieved.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A transmission comprising: a transmission housing; a dual clutchassembly having a first clutch, second clutch and a clutch housingconnectable to an engine output member, wherein the clutch housing isrotationally supported within the transmission housing; a first, second,third, fourth and fifth gear set, wherein the first gear set includes afirst gear in mesh with a second gear and a third gear, the second gearset includes a first gear in mesh with a second gear and a third gear,the third gear set includes a first gear in mesh with a second gear anda third gear, the fourth gear set includes a first gear in mesh with asecond gear and the fifth gear set includes a first gear in mesh with asecond gear; a first transmission input member rotatably supported inthe transmission housing and wherein each of the first gears of thethird and fourth gear sets are rotatably fixed for common rotation withthe first transmission input member and wherein the selective engagementof the first clutch of the dual clutch assembly transfers torque fromthe clutch housing to the first transmission input member; a secondtransmission input member rotatably supported in the transmissionhousing and wherein each of the first gears of the first and second gearsets are rotatably fixed for common rotation with the secondtransmission input member and wherein the second transmission inputmember is concentric with the first transmission input member and atleast partially surrounds the first transmission input member andwherein the selective engagement of the second clutch of the dual clutchassembly transfers torque form the clutch housing to the secondtransmission input member; a first countershaft rotatably supportedwithin the transmission housing and spaced apart from and parallel withthe first and second transmission input members, wherein the second gearof the first gear set, the third gear of the second gear set, the thirdgear of the third gear set and the second gear of the fourth gear setare each selectively connectable for common rotation with the firstcountershaft; a second countershaft rotatably supported within thetransmission housing and spaced apart from and parallel with the firstand second transmission input members, wherein the third gear of thefirst gear set, the second gear of the second gear set, the second gearof the third gear set and the first gear of the fifth gear set are eachselectively connectable for common rotation with the secondcountershaft; a third countershaft rotatably supported within thetransmission housing and spaced apart from and parallel with the firstand second transmission input members, wherein the second gear of thefifth gear set is selectively connectable for common rotation with thethird countershaft; and five synchronizer assemblies for selectivelycoupling at least one of the gears of the first, second, third, fourthand fifth gear sets with at least one of the first countershaft, thesecond countershaft and the third countershaft, and wherein theselective engagement of the first and second clutches of the dual clutchassembly interconnects the dual clutch housing with at least one of thefirst and the second transmission input members and the selectiveengagement of at least one of the five synchronizer assembliesestablishes at least one of a forward or reverse speed ratio.
 2. Thetransmission of claim 1 wherein a first of the five synchronizerassemblies selectively connects the second gear of the first gear setand the third gear of the second gear set to the first countershaft. 3.The transmission of claim 2 wherein a second of the five synchronizerassemblies selectively connects the third gear of the first gear set andthe second gear of the second gear set to the second countershaft. 4.The transmission of claim 3 wherein a third of the five synchronizerassemblies selectively connects the third gear of the third gear set andthe second gear of the fourth gear set to the first countershaft.
 5. Thetransmission of claim 4 wherein a fourth of the five synchronizerassemblies selectively connects the second gear of the third gear setand first gear of the fifth gear set to the second countershaft.
 6. Thetransmission of claim 5 wherein a fifth of the five synchronizerassemblies selectively connects the second gear of the fifth gear set tothe third countershaft.
 7. The transmission of claim 1 wherein the firstgear set is adjacent the dual clutch assembly, the second gear set isadjacent the first gear set, the third gear set is adjacent the secondgear set, the fourth gear set is disposed between the third gear set andan end wall of the transmission housing and the fifth gear set isco-planar with the fourth gear set.
 8. The transmission of claim 1further comprising a first countershaft transfer gear fixed to the firstcountershaft for common rotation with the first countershaft, a secondcountershaft transfer gear fixed to the second countershaft for commonrotation with the second countershaft and a third countershaft transfergear fixed to the third countershaft for common rotation with the thirdcountershaft and wherein the first, second and third countershafttransfer gears transfer torque from at least one of the first, secondand third countershafts to a transmission output member.
 9. Thetransmission of claim 8 wherein the transmission output member is a gearthat meshes with the each of the first, second and third countershafttransfer gears.
 10. The transmission of claim 8 further comprising apark gear fixed to the third countershaft for common rotation with thethird countershaft wherein the park gear is configured to preventrotation of the third countershaft and third countershaft transfer gear.11. A transmission comprising: a transmission housing; a dual clutchassembly having a first clutch, second clutch and a clutch housingconnectable to an engine output member, wherein the clutch housing isrotationally supported within the transmission housing; a first, second,third, fourth and fifth gear set, wherein the first gear set includes afirst gear in mesh with a second gear, the second gear set includes afirst gear in mesh with a second gear and a third gear, the third gearset includes a first gear in mesh with a second gear and a third gear,the fourth gear set includes a first gear in mesh with a second gear,and the fifth gear set includes a first gear in mesh with a second gear;a first transmission input member rotatably supported in thetransmission housing and wherein each of the first gears of the thirdand fourth gear sets are rotatably fixed for common rotation with thefirst transmission input member and wherein the selective engagement ofthe first clutch of the dual clutch assembly transfers torque from theclutch housing to the first transmission input member; a secondtransmission input member rotatably supported in the transmissionhousing and wherein each of the first gears of the first and second gearsets are rotatably fixed for common rotation with the secondtransmission input member and wherein the second transmission inputmember is concentric with the first transmission input member and atleast partially surrounds the first transmission input member andwherein the selective engagement of the second clutch of the dual clutchassembly transfers torque form the clutch housing to the secondtransmission input member; a first countershaft rotatably supportedwithin the transmission housing and spaced apart from and parallel withthe first and second transmission input members, wherein the second gearof the first gear set, the third gear of the second gear set, the thirdgear of the third gear set and the second gear of the fourth gear setare each selectively connectable for common rotation with the firstcountershaft; a second countershaft rotatably supported within thetransmission housing and spaced apart from and parallel with the firstand second transmission input members, wherein the second gear of thesecond gear set, the second gear of the third gear set, the second gearof the third gear set and the first gear of the fifth gear set are eachselectively connectable for common rotation with the secondcountershaft; a third countershaft rotatably supported within thetransmission housing and spaced apart from and parallel with the firstand second transmission input members, wherein the second gear of thefifth gear set is selectively connectable for common rotation with thethird countershaft; a first countershaft transfer gear fixed to thefirst countershaft for common rotation with the first countershaft; asecond countershaft transfer gear fixed to the second countershaft forcommon rotation with the second countershaft; a third countershafttransfer gear fixed to the third countershaft for common rotation withthe third countershaft; a park gear fixed to the third countershaft forcommon rotation with the third countershaft wherein the park gear isconfigured to prevent rotation of the third countershaft and thirdcountershaft transfer gear when engaged; and five synchronizerassemblies for selectively coupling at least one of the gears of thefirst, second, third, fourth and fifth gear sets with at least one ofthe first countershaft, the second countershaft and the thirdcountershaft, and wherein the selective engagement of the first andsecond clutches of the dual clutch assembly interconnects the dualclutch housing with at least one of the first and the secondtransmission input members and the selective engagement of at least oneof the five synchronizer assemblies transfers torque from at least oneof the first, second, third, fourth and fifth gear sets to at least oneof the first, second and third countershafts and to at least one of thefirst, second and third countershaft transfer gears to establish atleast one of a forward or reverse speed ratio.
 12. The transmission ofclaim 11 wherein a first of the five synchronizer assemblies selectivelyconnects the second gear of the first gear set and the third gear of thesecond gear set to the first countershaft.
 13. The transmission of claim12 wherein a second of the five synchronizer assemblies selectivelyconnects the third gear of the first gear set and the second gear of thesecond gear set to the second countershaft.
 14. The transmission ofclaim 13 wherein a third of the five synchronizer assemblies selectivelyconnects the third gear of the third gear set and the second gear of thefourth gear set to the first countershaft.
 15. The transmission of claim14 wherein a fourth of the five synchronizer assemblies selectivelyconnects the second gear of the third gear set and first gear of thefifth gear set to the second countershaft.
 16. The transmission of claim15 wherein a fifth of the five synchronizer assemblies selectivelyconnects the second gear of the fifth gear set to the thirdcountershaft.
 17. The transmission of claim 11 wherein the first gearset is adjacent the dual clutch assembly, the second gear set isadjacent the first gear set, the third gear set is adjacent the secondgear set, the fourth gear set is disposed between the third gear set andan end wall of the transmission housing and the fifth gear set isco-planar with the fourth gear set.
 18. The transmission of claim 11further comprising a transmission output member, wherein thetransmission output member is a gear that meshes with the each of thefirst, second and third countershaft transfer gears.